The present invention relates to friction clutches in general, and more particularly to improvements in friction clutches of the type having arrangements serving to automatically compensate for wear upon various component parts such as the friction linings of the so-called clutch disc or clutch plate.
Friction clutches with automatic wear compensating units or arrangements are disclosed or referred to, for example, in published German patent applications Serial Nos. 42 39 291, 43 06 505, 42 39 289, 43 22 677, 44 18 026, 44 31 641 and 195 10 905. Such friction clutches can be utilized with advantage in the power trains of motor vehicles, e.g., to transmit or to interrupt the transmission of torque between a prime mover (such as a combustion engine or a hybrid including an engine and a motor) and a variable-speed (manual, automated or automatic) transmission.
As a rule, a friction clutch comprises a rotary housing which is coaxial with and spaced apart from the clutch disc, a pressure plate which rotates with the housing and is movable axially between the housing and the clutch disc, and at least one clutch spring (normally a diaphragm spring) which is caused or permitted to bias the pressure plate against the adjacent friction linings of the clutch disc so that the latter is urged against a driven counterpressure plate and shares (with or without slip) the rotary movement of the housing. The housing (as well as the counterpressure plate) receives torque from the prime mover and can rotate the pressure plate as well as the diaphragm spring. The latter reacts against the housing and bears upon the pressure plate at least in the engaged condition of the clutch.
The wear compensating unit is arranged to move (when necessary) the diaphragm spring away from the housing to an extent commensurate with the extent of wear upon various component parts (particularly the friction linings) of the clutch. Furthermore, the wear compensating unit is or can be designed to ensure that the amount of energy stored by the diaphragm spring remains at least substantially constant during the useful life of the power train. In many or most instances, the wear compensating unit is installed (at least in part) between the diaphragm spring and the adjacent (inner) side of the housing. Reference may be had, for example, to commonly owned U.S. Pat. Nos. 5,409,091 (granted Apr. 25, 1995 to Reik et al. for "AUTOMATICALLY ADJUSTABLE FRICTION CLUTCH") and 5,450,934 (granted Sep. 19, 1995 to Maucher for "FRICTION CLUTCH").
The disclosures of all U.S. and foreign patents and patent applications identified in the specification of the present application are incorporated herein by reference. The disclosure of the German priority application Serial No. 199 24 954.7 (filed May 31, 1999) is also incorporated herein by reference.